ML19319B752
| ML19319B752 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/23/1977 |
| From: | George T, Lingenfelter J TOLEDO EDISON CO. |
| To: | |
| Shared Package | |
| ML19319B643 | List: |
| References | |
| NUDOCS 8001270213 | |
| Download: ML19319B752 (2) | |
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V TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-77-44 DATE OF EVENT: July 29, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Indication variation on two Stean Generator level transmitters (LT-SP9A6 and LT-SP9A7) was greater than the allowed differential tolerance of 10 inches Conditions Prior to Occurrence: The plant was in Mode 3, with Power (MWT) = 0 and Load (MRE) = 0.
Description of Occurrence: At 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br /> on July 29, 1977, Instru=ent and Control personnel were calibrating and repairing tubing leaks on one Steam Generator level transmitter at a ti=e (LT-SP9A6, 9A7 and 9B9). Each transmitter was restored to service uithin 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. At 1045 hours0.0121 days <br />0.29 hours <br />0.00173 weeks <br />3.976225e-4 months <br /> while performing ST 5099.01, Miscellanecus Instrument Shift Checks, 2 Steam Generator level transmitter india.ations on LT-SP9A6 and LT-SP9A7 were greater than the allowed differential colerance of 10 s
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inches. This placed the unit in the Action Statement of Technical Specification d
3.3.2.2.(b).
Designation of Aeoarent Cause of Occurrence: After a Maintenance Work Order was issued, it was discovered that the "ent valves on the transmitter body were leaking causing a loss of level indication in the Contrrl Room. The vent valves were never properly tightened during the calibration.
l Analysis of Occurrence: Since (he indications never went out of the tolerance that would require a manual trip of the Steam and Feedwater Rupture Control Systa:
Channel, the Channel re=ained operable and there was no threat to the health and safety of the public or Station personnel.
Corrective Action: SFRCS level indicators were monitored closely to determine if any of the channels must be tripped as per Action Statement #13 of Table 3.3-11.
The vent valves were tightened to stop the leaks and Steam Generator level indica-tion was returned to normal.
Investigation of this problem is continuing with the vendor (Rosemont).
Failure Data: Stes: Generator level was inoperable on one prior event (NF-33-7 7-21),
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y but the cause of the event was a deficient design in the power supplies.
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